Yuri wrote at 2007-2-8 15:09 +0100:
> I need a field in zope object which act as a sequence. I mean every
>time I create an object, the value is the previous sequence value of the
>last object created + 1.
> also I need to browse the objects by sequence (from the object 1 to the
>last, by the sequence number)
> I think I need a catalog FieldIndex to store the sequence for searches,
>a property in the object.
> Can I use the catalog to retrieve the max value of the index, so when I
>create the object, I just add 1 and store it in the property?
You can -- but it is unsafe (concurrent transaction can see the same
value and you may use the same id for different objects).
A better alternative is to implement the sequence object directly --
as a persistent object with an integer attribute (and a method to
fetch the next value).
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